This invention relates to contact lenses, and more particularly, to soft contact lenses whereby visual activity is increased by increasing the amount of light absorbed by the cones of the retina.
The retina contains two types of photo receptors: rods and cones. In 1939, Stiles showed that light rays which strike a cone perpendicular to its surface are perceived as brighter than those that do not strike in a perpendicular fashion. See xe2x80x9cThe Luminous Efficiency of Monochromatic Rays Entering the Eye Pupil at Different Points and a New Colour Effectxe2x80x9d by W. S. Stiles from The National Physical Laboratory, pp. 90-118, of 16 Feb., 1938. Additionally please see xe2x80x9cThe Scotopic Stiles-Crawford Effectxe2x80x9d by Van Loo, Jr. and Enoch in Vision Res. Vol. 15 pp 1005-1009 1975 and Wavelength Discrimination of the Peripheral Cones and Its Change with Rod Intrusionxe2x80x9d by Stabell and Stabell, Vision Res. Vol 17, pp 423-426,1977.
To date, this effect has been primarily a clinical phenomenon. It has not been utilized for the improvement of vision.
The present apparatus comprises a lens body of conventional soft contact lens composition, having a generally spherical concave back surface adapted m fit the cornea of the eye, and a generally convex front surface. The lens preferably includes a prism ballast to ensure correct orientation. The lens of the present invention is made of opaque a other substances which generally do not transmit light. In the process, the eye is mapped with a conventional field test to determine the diseased portion of the eye and those portions of the eye having optical perception. Through the lens surface, circular channels or xe2x80x9cpinholesxe2x80x9d which traverse the entire thickness of the lens are placed In an area which maps and therefore corresponds to the potion of the retina having optical perception. Light incident on the underlying portion of the retina having optical perception through the pinholes provides improved vision. These pinholes can be made in the form of channels. Such channels further increase tear distribution under the lens with improved comfort to the wearer. The channels additionally provide increased oxygen flow to the cornea and lens, thereby diminishing the physiological burden occasioned by standard soft contact lens.
There are a number of individuals afflicted by retinal disease. In these individuals the total number of retinal cones has been dramatically reduced as a result of the disease process. The present invention seeks to improve the remaining visual acuity by altering the manner in which ambient light is delivered to those cones not destroyed by the disease process.
By placing a number of xe2x80x9cholesxe2x80x9d or channels through an opaque contact lens surface in an area on the lens which corresponds with the remaining visual field, the light passing through these holes is faced to strike the posterior retinal surface in a perpendicular manner. The physiological effect is an overall increase in visual acuity as a result of increased light reception. It is believed that this improvement is related to the so-called Stiles-Crawford Effect of the First Order.
The portion of the retina not having sufficient light sensitivity to contribute to meaningful perception is covered by the opaque portion of the lens-thin portion not having the pinholes. Light is prevented from being perpendicularly incident on the diseased portions of the retina. Specular reflection of this light from the diseased retina is inhibited
Because each person suffering from retinal disease will have a specific field defect unique to their own process, the lens must possess a means by which to maintain axial orientation thereby insuring that the opacified portion of the lens does not occlude the remaining visual field. This is conventionally done with a prism to bias the lens and prevent lens rotation.